Help Me Compare the 600's

[BigChickenStrips]

i did NOT say i was bored of my bike- i said it did not have the acceleration of a 600 class fuel injected sport bike going up a 9% grade at 5000ft+ of elevation.

i love my bike. and i hope to be albe to afford to keep it to ride around town. and even if i did get rid of it, i guarnetee i'd be a much better rider after only a few months than someone who got at 600 as a first bike. i stand by telling people that the 250 is a great starter bike becasue it is.

[dieziege]

What's that thing about "...protest too much?"

You gotta admit it was funny. Or maybe you don't, but it was. As for really thinking you're bored, I've got 4300mi on mine and I'm not... unless you suffer from ADD I don't figure you really are.

[Randy]

I live at a relatively high location, about 5600 feet above sea level. No idea how far that is in meters. I hear that around here the Kawasaki 600RR runs kind of junky without a mixture of race gas.

Evidently the high altitude, high compression mix doesn't go over so well with just plain high octane gasoline.

I do hear that with race gas, those 600RRs really scream though.

[BigChickenStrips]

i do have ADD, but the problem is not the bike, its who i choose to ride with. they all have much larger bikes and as much as i love the 250 and its awesome for new riders and for mixed rides (had less trouble keeping up with cruisers and dual sports on one of the last group rides). but if i am going to continue to ride with the bigger bikes, by next year i'll be ready for something bigger. its not a boredom thing but i feel like i am approaching the limits of the bike. (i can scrape pegs on both sides on a regular basis, and i dont have knee sliders yet to get that down). i have recieved some excelent instruction from some very experienced local bikers about body positioning, acceleration, cornering, lean, and all the other things that you need to know to be a good rider. had i gotten a gixxer 600 3 months ago, i would have immedialty started workign on learning roll-on power wheelies, and i'd have chickenstrips that were 2" on either side. but if i can use/control the power and handling of a 600 theres nothing wrong with upgrading. i didnt buy a 250 thinking it was the last bike i'd ever buy, i bought it as a firt bike and it has been a great one, but like most people, its a starter bike.

[dieziege]

I'z just playin' wid'ya....

Dunno if you care about any of this, but it might broaden your range of acceptable bikes so I'll toss it out there FYI... HP decreases by altitude even with FI...

The density of the atmosphere varies based on altitude, air temp, humidity, and a few other factors... if you are at 5000' but it the air temp is 72(f), the "effective" altitude is higher than if the temp was 49(f). In aviation this is called Density Altitude and it's critically important because it impacts not only engine HP but how well the wings lift.

If you were riding at 5000', and the air temp was 80 degrees and humid all that adds up to a density altitude (the altitude your engine thinks it is) of close to 7800 feet! And, since you lose HP as your density altitude goes up, even a fuel injected engine would only put out about 80% of the sea level HP.

The reason that is true is that the air is about 79% as dense as "standard" air.

That's point one... now we get to the mixture being off. Ideal mixture is around 14.7:1 air:fuel mixture. In other words, for every 14.7 pounds of air one pound (sixth of a gallon roughly) of gas is added. That's what your carb is set up for (approximately). Now, this is simplistic... but if we assume an ideal mixture at sea level and an 80% density at our actual altitude, the mixture is going to be roughly 11.7:1 (this is wrong, but it isn't as wrong as it could be).

When does an engine stop running right because of too much fuel? As it works out, 8:1 is about the richest mixture that will fire in most engines. 12.8:1 is considered a "reasonable" mixture to intentionally choose in many cases. Not ideal but no short term harm. Frankly I'm not sure off the top of my head what the percentage loss as the mixture goes up but it's not huge until the engine starts running rough.

What's all that mean? It means that most of the loss you are seeing is the air density not the bad mixture. For our 28RWHP bike that means we've got maybe 19-20HP available (and that's at ~12KRPM) at 5000' on a warm day. Now take a 70HP carbed bike and do the same thing.... you've still got about 50HP left... With FI you've got 56HP left.

Point being... FI is an advantage (especially if you want optimum fuel economy while crossing mountains) but it isn't the huge advantage compared to just having more HP to start with.

My next bike will still have FI though.

[Dichotomous]

+1. air density changes will affect all NA motors. The only way around this is to have a very intelligent forced induction system. and the only reason that works is that with, say, a turbo and wastegate, is that the computer can moniter the oxygen levels via the o2 sensor, and vary the amount of boost and gas to achieve the same power level. though I think even this set up would work more efficiently at lower levels too as it could add more gas for the same boost pressure.

[BigChickenStrips]

so basically your saying i need nitrous! get a scuba-style tank strapped to my back, just let it run all the time. sweetness. that would be cheaper than buying another bike anyway because i have recently discovered i am poor.

[Dichotomous]

nitrous does not equal boost. Boost is where you stuff more air into the cylinders via increasing (or boosting) the air pressure coming in. Nitrous being called boost seems to come from two things, fast and furious, and the game "burnout" where captain jackass narrator/commentor says just about everything that game developers think sound cool. anyways, forced induction = boost, nitrous = nitrous

[dieziege]

You only just now discovered that? That's lucky! I figured out I was too broke at like 14.

Look at it this way... A turbo two fiddy set to hold sea-level pressures (in other words, doing nothing until you go into the mountains) would leave your bike with more horsepower than a GS500 by the time you reached 5000 feet...and more HP than some "real" bikes if you were up in the rockies. That's what turbocharged airplane engines typically do....boost isn't for power but for high altitude operation.

Dial in a couple pounds of extra boost and you've got a definite contender for special crotch rocketness awards.

Another secret... you don't need the OX sensor or anything too fancy... you just need to maintain a given air density. That's a factor of manifold pressure and temperature... Start surfing junkyards for the turbo from an old mitsubishi or the like... a little time with the guys in the physics dept. of your local university will get you everything else you need (those guys often have cool tools like TIG welders and machine tools available to them).... and away you go!

[jmillheiser]

Ninja 600 (and 636 Twisted Evil ) - pretty standard 600 supersport
CBR600F4i - if your over about 5'9" you may find it cramped
sv 650 - hard to beat for riding twisty roads, cheaper on insurance to boot
gixxer 600 - pretty standard 600 supersport
ducati 999R (just kidding) - track bike with lights and mirrors
triumph 675 - handling to match any other 600 supersport plus a broader powerband and sweet sounding engine.

if your worried about insurance costs I would go for the SV650, otherwise all the 600s will be pretty much the same, though the triumph has a broader powerband than the other 600 class bikes.

you might also check out the SV1000. Its pretty comparable to the 600s in performance but a tad roomier and loads of power at any RPM